Comment by gabiruh

I like Perl's Data::ParseBinary (https://metacpan.org/pod/Data::ParseBinary)

    my $s = Struct("foo",
        UBInt8("a"),
        UBInt16("b"),
        Struct("bar",
            UBInt8("a"),
            UBInt16("b"),
        )
    );
    my $data = $s->parse("ABBabb");
    # $data is { a => 65, b => 16962, bar => { a => 97, b => 25186 } }